Concepts Of Physics MCQ Edition [Volume 2]
- Exam
- Concepts Of Physics MCQ Edition [Volume 2]
- Subject
- Physics
- Chapter
- Bohr's Model and Physics of the Atom
Concepts Of Physics MCQ Edition [Volume 2] · Physics · Bohr's Model and Physics of the Atom
Assume that under specific conditions, hydrogen atoms are permitted...
Assume that under specific conditions, hydrogen atoms are permitted to undergo only those transitions where the principal quantum number changes by . Determine the smallest wavelength emitted by hydrogen.
Options
- A
- B
- C
- D
Correct answer
B.
Step-by-step solution
The wavelength of the emitted photon is given by the Rydberg formula:
\dfrac{1}{\lambda} = R \left(\dfrac{1}{n_1^2} - \dfrac{1}{n_2^2} \right)
For the smallest wavelength, the energy difference between the transition levels must be maximum. Given the condition that the principal quantum number changes by , we have . The maximum energy difference occurs for the lowest possible values of and .
Thus, the transition is from to .
Substituting these values into the formula:
\dfrac{1}{\lambda} =R \left(\dfrac{1}{1^2} - \dfrac{1}{3^2} \right) =R \left( 1 -\dfrac{1}{9} \right) = \dfrac{8R}{9}
\dfrac{9}{8R}
Using the standard value \dfrac{1}{R} \approx:
\dfrac{9}{8} \times
The closest value among the given options is .
\dfrac{1}{\lambda} = R \left(\dfrac{1}{n_1^2} - \dfrac{1}{n_2^2} \right)
For the smallest wavelength, the energy difference between the transition levels must be maximum. Given the condition that the principal quantum number changes by , we have . The maximum energy difference occurs for the lowest possible values of and .
Thus, the transition is from to .
Substituting these values into the formula:
\dfrac{1}{\lambda} =R \left(\dfrac{1}{1^2} - \dfrac{1}{3^2} \right) =R \left( 1 -\dfrac{1}{9} \right) = \dfrac{8R}{9}
\dfrac{9}{8R}
Using the standard value \dfrac{1}{R} \approx:
\dfrac{9}{8} \times
The closest value among the given options is .